The present invention relates to a radiator fan controller for preventing the generation of an excessive temperature rise by scavenging an engine compartment.
A conventional cooling system for a water-cooled engine mounted on a motor vehicle circulates a coolant which has become hot after cooling the engine by an radiator to cool the coolant therein and supplies it to the engine again, and is provided with a motor-driven radiator fan to accelerate heat exchange in the radiator. The motor-driven radiator fan is generally controlled by combining various parameters, such as vehicle speed and the operating conditions of an air conditioner, with the temperature of coolant as a main condition, as disclosed in Japanese Patent Application Laid-Open Publication No. Hei. 5-98963.
Such a conventional radiator control, however, only cools a condenser of an air conditioner as long as it becomes hot, and controls the operation of a radiator fan, basically, in order to maintain the coolant temperature of an engine properly. Therefore, even if the temperature in an engine compartment becomes high at the time of idling immediately after heavy load driving, for example, pulling a heavy cargo, such as a leisure boat or an engine stalled vehicle, or hill climbing, or low-speed driving due to traffic congestion, a radiator fan will not operate unless the temperature of coolant rises to higher temperature than a predetermined value.
Under such situations, ambient temperature in the engine compartment is sometimes excessively high although the coolant temperature of the engine is maintained properly, so that various types of components disposed in the engine compartment constituted of a material such as rubber or resin may have thermal effects, thus causing the degradation of durability thereof. Therefore, a conventional method of maintaining the temperature in the engine compartment properly has requited some measures such as the addition of a new apparatus for forcibly scavenging the engine compartment.
It is therefore an object of the present invention to provide a radiator fan controller which is capable of lowering the temperature in the engine compartment by positively scavenging the engine compartment if the temperature in the engine compartment is high enough to require scavenging.
In accomplishing the foregoing object, according to a first aspect of the invention, a radiator fan controller comprises engine compartment temperature determining means for determining an engine compartment temperature state as a high temperature state requiring scavenging of an engine compartment when the temperature in the engine compartment is equal to or higher than a predetermined temperature level under a lower vehicle speed than a predetermined speed level, or under a stopping state, and engine compartment scavenging means for scavenging the engine compartment by operating a radiator fan when the above-mentioned determining means determines the temperature in the engine compartment as being high enough to require scavenging of the engine compartment.
According to a second aspect of the invention, a radiator fan controller for operating a radiator fan when a coolant temperature is equal to or higher than a predetermined level, comprises engine compartment temperature determining means for determining an engine compartment temperature state as a high temperature state requiring scavenging of an engine compartment when the temperature in the engine compartment is higher than a predetermined temperature level and when a vehicle speed is lower than a predetermined speed level, or under a stopping state, and engine compartment scavenging means for scavenging the engine compartment by operating the radiator fan for a predetermined period of time once the above-mentioned determining means determines the temperature in the engine compartment as being high enough to require scavenging of the engine compartment regardless of coolant temperature, vehicle speed, or engine compartment temperature sensed for a predetermined period of time.
In other words, the first aspect of the invention positively prevents various types of components disposed in the engine compartment from having thermal damage being suffered from the high temperature in the engine compartment by operating the radiator fan to scavenge the engine compartment when the temperature in the engine compartment is equal to or higher than a predetermined temperature level under a low-speed driving condition that vehicle speed is lower than a predetermined speed level, or a stopping condition.
The second aspect of the invention positively prevents various types of components disposed in the engine compartment from having thermal damage being suffered from the high temperature in the engine compartment by operating the radiator fan under a condition that the engine coolant temperature is equal to or higher than the predetermined level, and through scavenging the engine compartment by operating the radiator fan regardless of coolant temperature, vehicle speed, or engine compartment temperature for a predetermined time once the temperature in the engine compartment is determined to be equal to or higher than a predetermined temperature level under such a low-speed driving state that vehicle speed is equal to or lower than a predetermined speed level, or a stopping state to maintain the coolant temperature properly and lower the temperature in the engine compartment.